Special telescopes for directly observing the prominences of the sun are known in the art. However, telescopes of this special type are costly and therefore unavailable to most telescope users of amateur status.
One type of adapter for enabling a conventional astronomical telescope to be utilized for observing solar phenomena is disclosed in the U.S. Pat. No. 3,351,408 to Krewalk. The adapter essentially includes a green filter glass for filtering out ultra-violet and infra-red rays which can cause permanent injury to the retina of the eye, and an aluminum-coated quartz lens for attenuating the light passing through the adapter. One end of the adapter housing is intended to be connected with the eye-piece holder of the telescope and the other end receives a conventional eyepiece or ocular. When the telescope, adapter, and eyepiece are connected together the quartz lens effectively increases the focal length of the telescope for enabling the filtered, attenuated image of the sun to be viewed by the displaced eyepiece. However, although the adapter of Krewalk is suitable for permitting direct observation of certain surface phenomena of the sun, such as sun-spot activity, it is not suited for enabling clear, direct observation of the prominences on the sun except during periods of solar eclipse.